spaceflight “passive” wireless sensors...project statement: develop wireless sensors that can be...

Spaceflight “Passive” Wireless

Sensors

Rachel Cueva | NASA GSFC Intern

MDSGC Student Research Symposium

27 July 2019

Introduction

Project Statement: Develop wireless

sensors that can be used on instruments

and spacecraft during flight and/or

integration and test that can provide a

significant increase in data acquisition

capabilities.

27 July 2019 Rachel Cueva | Spaceflight "Passive" Wireless Sensors 2

Why Go Wireless?

• Eliminates mass and clutter

associated with using wired

connections

• Significantly reduces cost

and time it takes to run tests

• Allows for spindle and

deployment mechanisms to

operate more efficiently

• Can more effectively collect

data in hard-to-reach

locations (vacuum chamber)

• Able to stay on flight as

passive item unless queried

Source: http://www.collectspace.com/news/news-081512a.html

27 July 2019 3Rachel Cueva | Spaceflight "Passive" Wireless Sensors

Background on ZigBee/XBee

• ZigBee: a packet-based RF protocol

that can be used to create low-rate

wireless personal area networks

– Low power, low duty cycle, low data

rate requirement devices

• XBee: physical radio module whose

name refers to form factor

Frequency

BandData Rate

Max. Indoor

Range

Max.

Outdoor

Range

Supply

Voltage

Operating

Current

2.4 GHz 250 kb/s 133 ft (40 m) 400 ft (120 m) 2.1 – 3.6 V ~40 mA

Xbee Module Specifications from Digi ZigBee RF Modules Documentation.

XBee S2C image from Digi.com.


Only device type that can

start a ZigBee network

(can only have one);

selects channel and PAN

ID (16-bit and 64-bit)

Can communicate with

other devices on network

and support low power

(sleep) modes

End Device

Can allow new devices

to join network and

route data packets

RouterCoordinator

ZigBee Network


ZigBee Network


Image from “Wireless body sensor networks for health-monitoring applications.”

XBee Operation

Transparent (AT) Mode

• Simple interface that

easily allows for data

to transmit through

XBees

• What you send is

exactly what you

receive

Application

Programming Interface (API) Mode

• Can send RF data to

multiple XBees

• Can configure devices

in network remotely

• Can view source

address of received

RF data


Programming Sensors


Electronics Mount


• Conducted XBee range test

– Nominal and in Thermal Chamber

– 1 ft and 10 ft distance for each

• 4 total types of tests

– 3 rounds of tests for each type

– 100 packets per test

Range Testing

Remote XBee

Local XBee

Set-Up for Thermal

Chamber Testing

(~1 ft away)


Range Testing (cont’d.)

Nominal (1ft) Nominal (10ft) Chamber (1ft) Chamber (10ft)

Avg. Success (%) 87.7 87.3 88 88

Avg. RSSI (dBm) -27.3 -50 -31.7 -46.3

• A greater negative RSSI

value indicates a weaker

signal

• 5 bars (full) for all 1ft

testing

• 4 bars (sometimes 3) for

all 10ft testing

Source:

https://www.digi.com/resources/documentation/Digidocs/90

001456-13/concepts/c_rssi_pin_and_signal_strength.htm


Future Work

• Short-Term Goals:

– Solder sensors onto perf board and verify sensor data

– Spindle testing

– Design other electronic mounts

– Implement API mode

– Develop XBee user guide document for future interns

• Long-Term Goals:

– Finalizing XBee package for official spindle testing in

a thermal/vacuum chamber

– Data transmission between XBee and phone


Acknowledgments

• Dr. Umesh Patel – my mentor (NASA GSFC)

• Konrad Bergandy (NASA GSFC)

• Matthew Hinkle (NASA GSFC)

• Benjamin Kennedy (NASA GSFC – Northrop

Grumman)

• Matthew Showalter (NASA GSFC)

• Brittany Whetzel and the NASA Internship

Program

• Maryland Space Grant Consortium


References

Hao, Y., & Foster, R. (2008). Wireless body sensor networks for health-

monitoring applications. Physiological Measurement, 29(11).

doi:10.1088/0967-3334/29/11/r01

Setting SAIL for history: Houston's hidden space shuttle opening to public

tours: CollectSPACE. (n.d.). Retrieved from

http://www.collectspace.com/news/news-081512a.html

Signal strength and the RSSI pin. (2017). Retrieved from

https://www.digi.com/resources/documentation/Digidocs/90001456-

13/concepts/c_rssi_pin_and_signal_strength.htm

XBee S2C DigiMesh 2.4 through-hole module w/ wire antenna. (n.d.).

Retrieved from https://www.digi.com/products/models/xb24cdmwit-001

Zigbee RF Modules. (2018). Retrieved from

https://www.digi.com/resources/documentation/digidocs/PDFs/900009

76.pdf


Questions?

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